The use of electrical machines of the type identified above finds increasingly widespread application in transport vehicles, in particular, in transport vehicles equipped with an internal-combustion engine and in which the electrical machines have the function of generating electrical energy during braking of the transport vehicle and of converting the electrical energy into motive force in given operating conditions. These transport vehicles are generally defined as hybrid vehicles or hybrid-propulsion vehicles.
The process of conversion of kinetic energy into electrical energy and of electrical energy into kinetic energy requires installation on board the motor vehicle of an additional system known as KERS (Kinetic Energy Recovery System), which comprises, in addition to the electrical machine of a reversible type, a unit for accumulation of the electrical energy, and a control unit connected to the electrical machine and to the accumulation unit.
Said additional system, albeit providing encouraging results from the standpoint of the reduction of consumption and pollutants, in effect, increases the weight and the overall dimensions of the transport vehicle, and in many cases the application of said type of additional system is still limited.